content: /*
   * Copyright 2011-2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ix;
  
  import java.util.Iterator;
  import java.util.concurrent.Callable;
  
  final class IxFlattenIterable<T, R> extends IxSource<T, R> {
  
      final IxFunction<? super T, ? extends Iterable<? extends R>> mapper;
  
      IxFlattenIterable(Iterable<T> source, IxFunction<? super T, ? extends Iterable<? extends R>> mapper) {
          super(source);
          this.mapper = mapper;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public Iterator<R> iterator() {
          if (source instanceof Callable) {
              return (Iterator<R>)(mapper.apply(checkedCall((Callable<T>)source)).iterator());
          }
          return new FlattenIterator<T, R>(source.iterator(), mapper);
      }
  
      static final class FlattenIterator<T, R> extends IxSourceIterator<T, R> {
  
          final IxFunction<? super T, ? extends Iterable<? extends R>> mapper;
  
          Iterator<? extends R> current;
  
          FlattenIterator(Iterator<T> it, IxFunction<? super T, ? extends Iterable<? extends R>> mapper) {
              super(it);
              this.mapper = mapper;
          }
  
          @SuppressWarnings("unchecked")
          @Override
          protected boolean moveNext() {
              Iterator<? extends R> c = current;
  
              while (c == null) {
                  if (it.hasNext()) {
                      Iterable<? extends R> inner = mapper.apply(it.next());
                      if (inner instanceof Callable) {
                          value = checkedCall((Callable<R>)inner);
                          hasValue = true;
                          return true;
                      }
  
                      c = inner.iterator();
  
                      if (c.hasNext()) {
                          current = c;
                          break;
                      } else {
                          c = null;
                      }
                  } else {
                      done = true;
                      return false;
                  }
              }
  
              value = c.next();
              hasValue = true;
  
              if (!c.hasNext()) {
                  current = null;
              }
              return true;
          }
  
      }
  
  }
  